Tag: bio-chemistry

Questions Related to bio-chemistry

Formation of ATP in respiration is called

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. Photophosphorylation

  2. Substrate phosphorylation

  3. Oxidative phosphorylation

  4. Phosphorylation

Show answer
Correct Option: C
Explanation:

The respiratory breakdown of glucose in the presence of oxygen is an oxidative process. During this process, several intermediates such as pyruvic acid, isocitric acid, succinic acid and oxalic acid are oxidized. Each oxidation step involves the release of 2 H which goes to reduce various coenzymes i.e. NAD+ and FAD. Reduced NAD+ and FAD released in the glycolysis and Krebs cycle finally reduce oxygen to water. This transfer of H+ and e- from NADH + H+ or FADH2 to oxygen is not a simple process and the direct transfer of electrons from coenzymes to oxygen is thermodynamically not possible. To facilitate this transfer, many intermediate cytochromes and other carriers are arranged in a series which transport electrons from NADH or FADH2 to oxygen. This sequence of electron carriers constitutes electron transport system. The electron transport proceeds from carriers that have low redox potential to those having high redox potential. The electron transport down to the energy gradient through electron transport system leads to the formation of ATP from ADP and inorganic phosphate. This generation of ATP is called oxidative phosphorylation. 

Thus, the correct answer is option C. 

Oxidative phosphorylation of cytoplasmic $NADH (H^+)$ takes place in

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. Cytosol

  2. E.R.

  3. Mitochondria

  4. Golgi bodies

Show answer
Correct Option: C
Explanation:

A large amount of NADH produced during glycolysis and Krebs cycle undergoes oxidation with phosphorylation of ADP to form ATP which is supported by mitochondrial electron transport assembly and ATP synthase which are integral protein complexes of the inner mitochondrial membrane. The electron transport assembly is comprised of a series of protein complexes that catalyze sequential oxidation-reduction reactions.

Thus, the correct answer is option C.

During carbohydrate metabolism, NADH is produced in which of the following locations?
I. Cytosol
II. Mitochondrial matrix
III. Nucleus.

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. I only

  2. II only

  3. I and II only

  4. I, II and III

Show answer
Correct Option: C
Explanation:

In  the cytoplasm, one glucose molecule breaks down into two pyruvate molecules, and creates two NADH molecules by glycolysis. Transformation of one pyruvate from cytosol to one acetyl CoA produces one NADH molecule in the mitochondrial matrix. During  each turn of Krebs cycle, each acetyl CoA is systematically processed through the cycle and produces three NADH molecules.

So, the correct option is 'I and II only'. 

Oxidation of one molecule of glucose yields 38 mols of ATP in the proportion of

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. 8 in cytosol and 30 in mitochondrion

  2. 30 in cytosol and 8 in mitochondrion

  3. 38 in cytosol 

  4. 38 in mitochondrion

Show answer
Correct Option: A
Explanation:
 Process  Site  Energy Release
 Glycolysis(breakdown of glucose into pyruvic acid)  In cytoplasm  2 ATP2 NADH
Decarboxylation(conversion of pyruvic acid into Acetyl co enzyme) mitochondria  2 ATP
 CItric Acid Cycle(Oxidation of acetyl co enzyme)(When cycle runs twice) mitochondria  8 NADH2 FADH2 GTP
 Total    10+28=38
So the correct option is "8 in cytosol and 30 in mitochondria".

The role of mitochondria in oxidative phosphorylation was explained by 

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. Leninger

  2. Embden

  3. Krebs

  4. Meyer hoff

Show answer
Correct Option: A
Explanation:

  • Oxidative phosphorylation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to produce ATP. In most eukaryotes, this takes place inside mitochondria. This was explained by Leininger
Thus, the correct answer is 'Leininger.'

In Kreb's cycle, how many oxidation (dehydrogenation) occur?

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. 4

  2. 6

  3. 2

  4. 1

Show answer
Correct Option: A
Explanation:

In Kreb's cycle the oxidation or dehydrogenation reaction occurs 4 times as follows:

  1. Isocitrate to alpha-ketoglutarate (NADH is formed)
  2. alpha-ketoglutarate to succinyl co-A (NADH is formed)
  3. Succinate to Fumarate (FADH$ _{2}$ is formed)
  4. Malate to oxaloacetate (NADH is formed)
Hence, the correct answer is '4'.

Which is formed in oxidative phosphorylation?

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. ATP in photosynthesis

  2. ATP in respiration

  3. $NADPH _2$ in photosynthesis

  4. $NADPH _2$ in respiration.

Show answer
Correct Option: B
Explanation:

Oxidative phosphorylation-


This process takes place in mitochondria. In this process ATP is formed when electron are transferred from 

NADH or $FADH _2$ to $O _2$

(B) ATP in respiration occurs or is formed in oxidation phosphorylation.

Two copper centers are component of

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. Cytochrome $bc _1$ complex

  2. NADH dehydrogenase complex

  3. ATP synthase complex

  4. Cytochrome c oxidase complex

Show answer
Correct Option: A
Explanation:

Option 'A' is correct.


Two copper centres two $W _a$ and $W _b$ are component of cytochrome $bc$, complex. $W _a$ contains two copper cone which are linked by two bridging cysteine residue, whereas $W _b$ is linked by there histidine residues.

How any molecules of water should be photolysed to form a $NADPH 2$ molecule ________.

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. 4

  2. 2

  3. 6

  4. 1

Show answer
Correct Option: A

In which of the following phosphorylation in absent?

bio-chemistry biological oxidation oxidative phosphorylation living organisms and energy production glycolysis

  1. Glycolysis

  2. Kreb cycle

  3. $C _4$ cycle

  4. ETS

Show answer
Correct Option: C
Explanation:

$C _4$ cycle or the Hatch-Slack pathway is a photosynthetic process in some plants. It is the first step in extracting carbon from carbon dioxide to be able to use it in sugar and other biomolecules. $C _4$ plants do not undergo phosphorylation due to their special mechanism to increase the $CO _2$ level for enzyme binding.

So, the correct answer is '$C _4$ cycle'.